×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Adding a 7.2kV load on a 4.16kV system

Adding a 7.2kV load on a 4.16kV system

Adding a 7.2kV load on a 4.16kV system

(OP)

We have a 4.16kV LRG system here at our plant.

There is a new piece of equipment which others are considering adding that will operate at 7.2kV.  I am told tha this equipment will have a peak demand of 1198kW and an average demand of 696kW.  In order to operate this machinary at 7.2kV we will have to obviously install a 4.16kV to 7.2kV step-up transformer somewhere on our system.  I am trying to take a preliminary look at some circuits to determine if we have the capacity for adding this transformer and picece of equipment.

Is there anything I should watch our for when looking at circuit capacity for adding this step-up transformer and equipment load.  I know the step-up transformer may need to be somewhat oversized due to starting effects with the 7.2kV equipment load.  Is there a typical value for oversizing this transformer that I can use to gauge capacity?

Is there anyting to watch out for in regards to this transformer being fed from a LRG system?  Other than cable insulation rating?

I'd appreciate any insights or comments on this as we are in the process of doing some preliminary reviewing.

RE: Adding a 7.2kV load on a 4.16kV system

Knowing the expected PF of the load, as well as, the nature and duration of the peak load would help for transformer sizing.

Alan

Democracy is two wolves and a sheep deciding what to have for dinner.  Liberty is a well armed sheep!
Ben Franklin

RE: Adding a 7.2kV load on a 4.16kV system

(OP)

From what I am told the load consists of two Gen-Sets which use synchronous motors.  Therefore I'm not sure that power factor would play a major issue in determining the size of the transformer.

I am not sure about the duration of the peak loading, I will have to find out.

We already have a circuit which a 100hp motor.  This new additional load at 1198 kw would be about a 1600hp motor equivelent.  We may be able to beef up our existing circuit to accomidate this new transforemr and equipment.

Others are arguing with me that we do not have the capacity on this cirucit and will need to tap another feed off of our utility transformer.   

RE: Adding a 7.2kV load on a 4.16kV system


you should look at the voltage drop everywhere on your system, specially when the motor will be started.  Could be a problem.

RE: Adding a 7.2kV load on a 4.16kV system

You are adding about 200 amps to your system. I would be checking everything.

RE: Adding a 7.2kV load on a 4.16kV system

(OP)
This piece of equipment will be replacing a 4.16kV piece of equipment that is already in place and has a 1000hp motor.  So really we are just talking about adding an additional 600hp.

I'm trying to get more information on the loads, such as exactly what size motor are used.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources